Cell Cycle
Cell Proliferation

Author: Gianpiero Pescarmona
Date: 18/03/2007


The cell cycle is the series of events that take place in a eukaryotic cell leading to its replication.
These events can be divided in two brief periods: interphase —during which the cell grows, accumulating nutrients needed for mitosis and duplicating its cellular components (DNA, proteins, lipids) —and the mitotic (M) phase, during which the cell splits itself into two distinct cells, often called "daughter cells".

The cell cycle consists of four distinct phases:

  • Interphase
    • G1 phase
    • S phase
    • G2 phase (collectively known as)
  • M phase. M phase is itself composed of two tightly coupled processes: mitosis, in which the cell's chromosomes are divided between the two daughter cells, and cytokinesis, in which the cell's cytoplasm divides forming distinct cells.

Cells that have temporarily or reversibly stopped dividing are said to have entered a state of quiescence called G0 phase.

Activation of each phase is dependent on the proper progression and completion of the previous one.

After division new cells need to take up nutrients from the environment (niche) to undergo a new cell division.

Cell cycle checkpoints

During the Cell Cycle there are 3 very important checkpoints:

  1. G1/S Checkpoint
  2. G2/M Checkpoint
  3. M/G1 Checkpoint

G1-> S Enlargement

p53 role

G2 -> M Enlargement

Cell cycle animation
Some connections to textbooks.....

The nucleus structure


Polyamine dependence of normal cell-cycle progression 2003

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